Re: PostgreSQL and HugePage

On Wed, Oct 20, 2010 at 10:10:00AM -0400, Tom Lane wrote:
> Robert Haas <robertmhaas(at)gmail(dot)com> writes:
> > On Tue, Oct 19, 2010 at 11:30 PM, daveg <daveg(at)sonic(dot)net> wrote:
> >> On Wed, Oct 20, 2010 at 04:08:37PM +1300, Mark Kirkwood wrote:
> >>> Heh - provided you specify
> >>> SHM_HUGETLB
> >>> in the relevant call that is :-)
>
> >> I had a patch for this against 8.3 that I could update if there is any
> >> interest. I suspect it is helpful.
>
> > I think it would be a good feature. Of course, we would need
> > appropriate documentation, and some benchmarks showing that it really
> > works.
>
> I believe that for the equivalent Solaris option, we just automatically
> enable it when available. So there'd be no need for user documentation.
> However, I definitely *would* like to see some benchmarks proving that
> the change actually does something useful. I've always harbored the
> suspicion that this is just a knob to satisfy people who need knobs to
> frob.
>
> regards, tom lane
>

Oracle apparently uses hugepages if they are available by first trying
with the SHM_HUGETLB option. If it fails, they reissue the command
without that option. This article does mention some of the benefits
of the larger pagesizes with large shared memory regions:

http://appcrawler.com/wordpress/?p=686

Regard,
Ken